We aim for Insulation Grade 5 for the entire house, with a Ua value of 0.40 or less—corresponding to the ZEH (Net Zero Energy House) level in Sapporo (Region 2 / assuming a total floor area of approx. 120㎡).

Wall Insulation

• Glass Wool (GW) 100mm / 24K + FP Board 75mm (externally applied)

Foundation Insulation (Exterior Insulation Type)

• When the crawl space is considered as part of the interior, exterior insulation is applied.

• FP Board 75mm (external application)

• In colder regions with deep frost depths, skirt insulation is applied to reduce foundation depth.

• This method is typically used when the entire first-floor crawl space is utilized for floor heating.

Floor Insulation

• When the crawl space is considered external (e.g., due to high water table or limited foundation budget), floor-level insulation is applied.

• FP Board 40mm on the bottom layer, topped with GW 150mm.

• The FP board acts as a windbreak layer to prevent cold air infiltration from beneath the floor.

Ceiling Insulation

• When the attic space is not in use, ceiling-level insulation is applied.

• Although blown-in glass wool is easy to install, it is difficult to reuse during renovation.

• Instead, GW 100mm / 24K is installed in three layers with care to ensure thermal performance.

Roof Insulation

• When the attic space is utilized, insulation is applied to the roof deck, not the ceiling.

• Similar to ceiling insulation, GW 100mm / 24K is installed in three careful layers.